New research reveals that the neural pathways for exploring a mental map are surprisingly different from those used for visual perception, shedding light on the very nature of imagination.
Close your eyes for a moment and picture the layout of your home. You can probably navigate the space in your mind, moving from the front door to the kitchen, picturing the furniture and the turns you’d need to take. This ability to conjure and explore a space that isn’t physically in front of you is a remarkable feat of the human brain. We often call it the "mind’s eye." For a long time, many neuroscientists assumed that when we use our mind’s eye, our brain is essentially creating a faint echo of a real visual experience, reusing the same neural machinery we rely on to see the world.
However, a groundbreaking study from researchers at the École normale supérieure in Paris challenges this long-held assumption. Their findings suggest that our brain has two distinct systems for navigating space: one for the world we see, and another, entirely separate one for the worlds we imagine.
The Spotlight of Attention
To understand the significance of this discovery, we first need to talk about spatial attention. Think of your attention as a mental spotlight. When you’re looking at a complex scene, like a crowded street, you can’t process everything at once. Instead, your brain directs this spotlight to specific areas, enhancing the processing of whatever falls within its beam while dimming the rest. Neuroscientists have long known that this function is primarily managed by the posterior regions of the brain, specifically the parieto-occipital areas. When you visually focus on something, these areas light up with activity, coordinating the spotlight of your perception.
The central question that researchers Anthony Clément and Catherine Tallon-Baudry wanted to answer was whether this same posterior-driven spotlight is used when we explore an image from memory. When you navigate your house in your mind, are you simply re-engaging that same visual attention network, or is something else going on?
A Mental Trip Across France
To find out, the researchers designed an elegant experiment. They recorded the brain activity of participants using electroencephalography (EEG) while they performed two different spatial tasks. The first was a standard visual perception task. The second, however, was a journey into the mind’s eye.
Participants were asked to recall the map of France from their long-term memory. This was a shape most of them knew well. They were then instructed to focus their mental spotlight on either the right or left side of their imagined map. At the end of this brief period of mental focus, the names of two French cities appeared on a screen. The participant’s job was to decide which of the two cities was closer to Paris, a task that required them to consult their internal map.
This clever design allowed the scientists to directly compare the brain’s activity when attention was directed externally (during visual tasks) versus internally (during the mental map task). If imagination and perception used the same tools, the brain activity patterns, particularly the alpha-band waves associated with attention, should have been similar in both scenarios.
Two Brains, Two Compasses
The results were striking and unexpected. While participants were perfectly capable of directing their attention within their mental maps—proving that the mind’s eye does indeed have a
